• 한국기계가공학회지
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• 제17권6호
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• pp.170-176
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• 2018

Recently, weapon system requires personal protection products due to the explosion of rapid-fire explosion, which is considered to be multi threat in modernization, complication and war against terrorism. However, the conventional Korean military bullet protection helmets are not suitable for wearing convenience and combatant interoperability in terms of ergonomic. In this paper, we propose a suitable 3D Scanning method for the head, and compare the measured 3D dimension with the existing 2D measurement value to identity the reliability. Reverse engineered soldier head using the quick surface method was realized with a perfect free-form surface and satisfactory tolerance range (${\pm}0.2mm$). Through the comparison of 3D and 2D measured head dimensions, the absolute error value was 0.73 mm on average and relative error was 0.35 %, confirming the high accuracy of the 3D scan modeling. Also, quick surface method using 3D scanner is suggested a fast and accurate skill for ergonomics in obtaining the head modeling needed for military's personal bullet protection helmet design.

• 제어로봇시스템학회논문지
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• 제13권10호
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• pp.962-969
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• 2007

In this paper, an approach is developed for relative state estimation of satellite formation flying. To estimate relative states of two satellites, the Extended Kalman Filter Algorithm is adopted with the relative distance and speed between two satellites and attitude of satellite for measurements. Numerical simulations are conducted under two circumstances. The first one presents both chief and deputy satellites are orbiting a circular reference orbit around a perfectly spherical Earth model with no disturbing acceleration, in which the elementary relative orbital motion is taken into account. In reality, however, the Earth is not a perfect sphere, but rather an oblate spheroid, and both satellites are under the effect of $J_2$ geopotential disturbance, which causes the relative distance between two satellites to be on the gradual increase. A near-Earth orbit decays as a result of atmospheric drag. In order to remove the modeling error, the second scenario incorporates the effect of the $J_2$ geopotential force, and the atmospheric drag, and the eccentricity in satellite orbit are also considered.

• Journal of applied mathematics & informatics
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• 제6권2호
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• pp.661-668
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• 1999

Reliability estimation using Gibbs sampler considered for modeling mixture exponential reliability problems. Gibbs sampler is developed to compute the features of the posterior distribution. Bayesian estimation of complicated functions requires simpler esti-mation techniques due to the mathematical difficulties involved in the Bayes approach. The Maximum likelihood estimator and the Gibbs estimator of reliability of the system are derived. By simula-tion risk behaviors of derived estimators are compared. model de-termination based on relative error is considered. A numerical study with a simulated data set is provided.

• 대기
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• 제34권1호
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• pp.23-34
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• 2024

The Korea Meteorological Administration has improved medium-range weather forecasts by implementing post-processing methods to minimize numerical model errors. In this study, we employ a statistical correction technique known as the minimum continuous ranked probability score (CRPS) to refine medium-range forecast guidance. This technique quantifies the similarity between the predicted values and the observed cumulative distribution function of the Unified Model Ensemble Prediction System for Global (UM EPSG). We evaluated the performance of the medium-range forecast guidance for surface air temperature and relative humidity, noting significant enhancements in seasonal bias and root mean squared error compared to observations. Notably, compared to the existing the medium-range forecast guidance, temperature forecasts exhibit 17.5% improvement in summer and 21.5% improvement in winter. Humidity forecasts also show 12% improvement in summer and 23% improvement in winter. The results indicate that utilizing the minimum CRPS for medium-range forecast guidance provide more reliable and improved performance than UM EPSG.

• 한국컴퓨터정보학회논문지
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• 제27권4호
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• pp.27-36
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• 2022

본 논문에서는 이러한 어류 가공 현장의 문제점을 개선하기 위해서 AI 머신 비전을 이용한 어류의 목표 중량 절단 예측기법을 제안한다. 제안하는 방법은 먼저 입력된 물고기의 평면도와 정면도를 촬영하여 이미지기반의 전처리를 수행한다. 그런 다음 RANSAC(RANdom SAMmple Consensus)를 사용하여 어류의 윤곽선을 추출한 다음 3D 모델링을 사용하여 물고기의 3D 외부 정보를 추출한다. 이어서 추출된 3차원 특징 정보와 측정된 중량 정보를 머신러닝하여 목표 중량에 대한 절단 지점을 예측하기 위한 신경망 모델을 생성한다. 마지막으로 제안기법을 통해 예측된 절단 지점으로 직접 절단한 뒤 그 중량을 측정하였다. 그리고 측정된 무게를 목표 무게와 비교하여 MAE(Mean Absolute Error) 와 MRE(Mean Relative Error)와 같은 평가 방법을 사용해 성능을 평가하였다. 그 결과, 목표 중량과 비교해 3% 이내의 평균 오차율을 달성하였다. 제안된 기법은 향후 자동화 시스템과 연계되어 수산업 발전에 크게 기여할 것으로 전망한다.

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1317-1326
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• 1999

As the integration ratio and operation speed increase, it has become an important problem to estimate the dissipated power during the design procedure as a method to reduce the TTM(time to market). This paper proposed a prediction model to estimate the maximum dissipated power of a CMOS logic gate. This model uses a calculational method. It was formed by including the characteristics of MOSFETs of which a CMOS gate consists, the operational characteristics of the gate, and the characteristics of the input signals. As the modeling process, a maximum power estimation model for CMOS inverter was formed first, and then a conversion model to convert a multiple input CMOS gate into a corresponding CMOS inverter was proposed. Finally, the power model for inverter was applied to the converted result so that the model could be applied to a general CMOS gate. For experiment, several CMOS gates were designed in layout level by $0.6{\mu}m$ layout design rule. The result by comparing the calculated results with those from HSPICE simulations for the gates showed that the gate conversion model has within 5% of the relative error rate to the SPICE and the maximum power estimation model has within 10% of the relative error rate. Thus, the proposed models have sufficient accuracies. Also in calculation time, the proposed models was more than 30 times faster than SPICE simulation. Consequently, it can be said that the proposed model could be used efficiently to estimate the maximum dissipated power of a CMOS logic gate during the design procedure.

• 대한전자공학회논문지SD
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• 제40권4호
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• pp.13-20
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• 2003

반도체 소자이론에 근거한 집적회로용 BJT의 역포화 전류 모델을 제시한다. 공정 조건으로부터 베이스 영역의 불순물 분포를 구하는 방법과 원형 에미터 구조를 갖는 Lateral PNP BJT와 Vertical NPN BJT의 베이스 Gummel Number를 정교하게 계산하는 방법을 제시한다. 제안된 방법의 타당성을 검증하기 위해 20V와 30V 공정을 기반으로 제작한 NPN BJT와 PNP BJT의 역포화 전류를 실측치와 비교한 결과, NPN BJT는 6.7%의 평균상대오차를 보이고 있으며 PNP BJT는 6.0%의 평균 상태오차를 보인다.

• 한국습지학회지
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• 제16권3호
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• pp.383-392
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• 2014

본 연구의 목적은 LISFLOOD 모형을 이용하여 범람해석을 수행하고, 그 결과를 FLUMEN 모형에 의해 작성된 홍수범람도와 비교함으로써 국내하천에 대한 LISFLOOD 모형의 적용성을 평가하는 것이다. 이를 위해서 파제 시나리오를 작성하여 LISFLOOD 모형을 이용한 범람해석에 적용하였으며, 파제 시나리오별 범람해석 결과를 평가하였다. LISFLOOD 모형을 이용한 파제 시나리오별 범람해석 결과, FLUMEN 모형에 의해 작성된 홍수범람도와의 각 파제 구간별 범람면적의 상대오차가 0.2% ~ 42% 정도로 파제 지점에 따라서 다소 상이한 결과를 나타내었다. 그러나 홍수위험지도 제작방법과 같이 파제 시나리오의 범람해석 결과를 중첩하여 작성된 두 모형의 최대 범람면적에서는 약 1.2%의 상대오차를 보임으로써 서로 유사한 결과를 나타내었다. 한편 LISFLOOD 모형은 입력자료의 구축이 용이한 격자형태의 DEM과 상류단 경계조건인 수문곡선만을 활용하여 범람해석을 할 수 있으며, 범람해석에 소요되는 시간이 FLUMEN 모형보다 짧은 것으로 나타났다. 그러므로 신속한 범람해석이 필요한 지역에 대해서는 LISFLOOD 모형의 활용이 가능할 것으로 판단된다.

• 한국안전학회지
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• 제32권2호
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• pp.7-13
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• 2017

An experimental study was conducted to identify the quantitative measurement bias for the bare-bead thermocouple (TC), which was widely used for measuring temperature in fire experiments. To this end, an apparatus could be controlled individually gas flow rate, preheating temperature and incident radiative heat flux was developed to simulate the thermal environments of fire. A relative measurement bias of bare-bead TC was evaluated with the comparison of double-shield aspirated TC. As a result, the relative measurement bias of bare-bead TC was gradually increased with the increase in radiative heat flux with constant gas temperature. The relative bias was also significantly increased with the decrease in gas temperature. Quantitatively, at the gas temperature of $20^{\circ}C$, the bare-bead TC had the relative bias of approximately 400% with the radiative heat flux of $20kW/m^2$ corresponding to thermal radiation level of the flashover. The present study was intend to provide fire researchers with methodologies for the reanalyses of temperature measured using bare-bead TC, radiation corrections, and validation of fire modeling.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.244-250
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• 1999

Active vibration control method for the reduction of vibration of structures have been developed. For the application of real structures active control system that has robustness must be designed because the mathematical model incompletely described has intrinsically modeling error. In this research we propose LQG/LTR method in designing control system with robustness. A combination of acceleration feedback and model-order reduction technique is used for the application of real structures and the computation efficiency. In case of such structures as the building and the tower the inter-story relative displacements represent an important constraint in seismic design. Therefore selection method of design parameters is also proposed in order to reduce the inter-story relative displacements.